Fig. 1. Experimental setup for measuring vibrations occurred by the generation of BSR noise. Two types of welded specimens were fabricated with different number of missing joints. (a) The specimens without and (b) with missing welded joints.
Fig. 2. Measured vibrations of two types of spot-welded specimens when the 5 Hz harmonic vibration was applied on the specimens.
Fig. 3. Parameters and experimental setup for measuring vibrations using the attached structure. The welding currents at ζ7 were controlled from 0 to 10 kA. All spot welds except for the weld at ζ7 were performed with a welding current of 7 kA.
Fig. 4. Measured vibration responses using the attached structure. (a) Attached on a rigid body and (b) attached on the welded structure.
Fig. 5. Measured vibration responses according to attached locations (ζD) when the welding current at ζ7 was (a) 7 kA and (b) 0 kA. The frequency shifting in the specific band occurred only at the vibration response on the defected spot (ζD = 0.6).
Fig. 6. The measured vibration responses at ζD = 0.6 according to welding currents from 0 to 10 kA. Only the frequency band in the shaded section varied with the welding currents.
Fig. 7. The measured bending stiffnesses with the welding currents. The estimated bending stiffness of welded joints was closer to that of a 2 mm thickness as the welding current increased.
참고문헌
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